A non-invasive brain stimulation technique shows promise in speeding speech recovery in stroke patients and improving memory and cognitive function in Alzheimer's patients, new research suggests.

The technique, called transcranial direct current stimulation (tDTS), involves applying weak electrical current, via electrodes to a person's head, for short periods of time.

In tests with recovering stroke patients with speech difficulties, investigators at University College London found that tDCS quickened the word-finding ability in stroke patients as well as healthy older adults.

In a separate study, Brazilian researchers at São Paulo's Mackenzie Presbyterian University used tDCS to test memory function in people with Alzheimer's and Parkinson's disease. They found that multiple sessions with tDCS increased visual recognition skills by 18% in the Alzheimer's patients, and the effects lasted a month. In a similar study with Parkinson's disease patients, tDCS improved memory by 20%.

This research was presented this week at the 19th annual meeting of the Cognitive Neuroscience Society in Chicago.